Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 26,867	$ 25,213
Less accumulated depreciation	4,722	3,688
Property, plant and equipment, net	22,145	21,525
Natural gas gathering and NGL transportation pipelines and facilities
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,037	6,349
Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,410	6,045
Pipelines and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,117	5,111
Barges and towing vessels
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	739	621
Terminals and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,222	2,757
Refineries and related assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,383	1,447
Land, building, office equipment and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,554	1,562
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,405	$ 1,321
Minimum | Natural gas gathering and NGL transportation pipelines and facilities
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Minimum | Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Minimum | Pipelines and related assets
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Minimum | Barges and towing vessels
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years
Minimum | Terminals and related assets
Property, Plant and Equipment [Line Items]
Estimated useful lives	4 years
Minimum | Refineries and related assets [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	13 years
Minimum | Land, building, office equipment and other
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Maximum | Natural gas gathering and NGL transportation pipelines and facilities
Property, Plant and Equipment [Line Items]
Estimated useful lives	40 years
Maximum | Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Estimated useful lives	46 years
Maximum | Pipelines and related assets
Property, Plant and Equipment [Line Items]
Estimated useful lives	51 years
Maximum | Barges and towing vessels
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Maximum | Terminals and related assets
Property, Plant and Equipment [Line Items]
Estimated useful lives	45 years
Maximum | Refineries and related assets [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	38 years
Maximum | Land, building, office equipment and other
Property, Plant and Equipment [Line Items]
Estimated useful lives	45 years